CN115824924A - High-temperature and high-pressure resistant imbibition visualization system and imbibition parameter measurement method - Google Patents

Abstract

The invention discloses a high-temperature and high-pressure resistant imbibition visualization system and an imbibition parameter measurement method, and relates to the technical field of imbibition parameter measurement. The ISCO pump is respectively connected with a first middle container and a second middle container in a first pipeline and a second pipeline through a three-way valve in the first pipeline, the first middle container is connected to the inside of the microfluidic branching device through a second needle valve and a first four-way valve in sequence, the second middle container is connected to the inside of the microfluidic branching device through a fourth needle valve and a second four-way valve in sequence, an imaging device is connected to the upper portion of the microfluidic branching device, the vacuum pump is connected to the second four-way valve through a sixth needle valve in the fourth pipeline, the pressure tracking pump is connected to the first four-way valve through a fifth needle valve in the third pipeline, and the water bath box is connected with a thermal fluid circulation interface of the microfluidic branching device. The imbibition visualization system realizes the simulation of the imbibition process under the conditions of high temperature and high pressure and the visualization observation of the effect of the complete imbibition process.

Description

High-temperature and high-pressure resistant imbibition visualization system and imbibition parameter measurement method

Technical Field

The invention relates to the technical field of imbibition parameter measurement, in particular to a high-temperature and high-pressure resistant imbibition visualization system and an imbibition parameter measurement method.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Imbibition refers to the process of displacement and replacement of non-wetting fluid by wetting phase fluid in porous media, and capillary force is the main process of imbibition. In the geological field, many experiments relate to simulation of an imbibition process, such as a shale oil exploitation process, the developed nano-scale pores of a shale oil reservoir have ultralow pore permeability characteristics, natural industrial stable capacity is usually not available, and large-scale hydraulic fracturing is needed for industrial development. In the hydraulic fracturing process, the fracturing flowback rate of the shale reservoir is low, a large amount of fracturing fluid is retained in the reservoir, and the retained fracturing fluid can extract shale oil through the seepage and displacement effect. Compared with the conventional reservoir, the pore size of the shale reservoir is nano-scale, and the capillary force is increased by multiple orders of magnitude, so that the imbibition oil displacement effect is more obvious and important. For example, in the process of sealing and storing a CO2 saline water layer, the saline water layer is an unavailable deep saline water layer, the mineralization degree of formation water is as high as 3-50 g/L, when CO2 is injected into the deep saline water layer, under the action of pressure gradient and concentration difference, CO2 can be greatly diffused in the saline water layer, water in the formation water is continuously taken away, the saline water concentration is continuously increased, and salt is crystallized and separated out when the saline water concentration exceeds the saturated concentration. The large production of salt crystals reduces the permeability of the saltwater layer, thereby hindering subsequent injection of CO2 and ultimately affecting the sequestration capacity of CO2 in the saltwater layer. Therefore, the method has important significance for determining the dynamic process of salt crystallization caused by CO2 injection into the saline water layer and the influence of the salt crystallization on the reservoir seepage capacity.

However, the inventors have found that the prior art simulation of imbibition processes suffers from the following disadvantages: the imbibition efficiency and the wetting angle are two important imbibition parameters reflecting the imbibition displacement action, wherein the imbibition efficiency determines the oil recovery, the wetting angle is closely related to the capillary force, and the change of the wetting angle determines the strength of the imbibition action. For the imbibition efficiency, the conventional experimental method mainly measures by a volume method or a mass method: taking the displacement process of shale oil as an example, the volume method is that a rock core of saturated oil is soaked in imbibition liquid, an oil phase is imbibed and displaced to the surface of the rock core to be aggregated into oil droplets and float up, and the imbibition oil displacement is read by collecting the oil droplets, so that the imbibition efficiency can be calculated, but the method has obvious defects that crude oil imbibed and displaced is easy to attach to the surface of a rock sample, the crude oil cannot be metered, so that the imbibition efficiency is subjected to errors, and the shale porosity is low, and the saturated oil quantity is small, so that the errors are not negligible; the mass method is to soak saturated oil in the imbibition liquid, calculate the imbibition efficiency by weighing the mass change of the core before and after imbibition, however, the imbibition process of the shale reservoir is very long, the imbibition liquid in the experimental process can be slowly evaporated, resulting in increased errors, and therefore the existing volume method experimental device can not accurately measure. For the measurement of the wetting angle, the traditional experimental method is to soak a core with a polished surface in imbibition liquid, then squeeze and inject a drop of oil below the core surface, the oil rises and adheres to the shale surface, the oil drop shape is shot after stabilization, and the image analysis measures the contact angle. At present, the existing experimental method for measuring the imbibition efficiency and the contact angle cannot meet the experimental requirements of high-temperature and high-pressure accurate measurement and imbibition process visualization. In addition, the existing experimental device can not visually observe the whole process of imbibition, namely visual conditions are lacked, so that the experimental effect of the whole simulation experiment is influenced.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a imbibition visualization system and an imbibition parameter measurement method with high temperature and high pressure resistance.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the invention provides a high-temperature and high-pressure resistant imbibition visualization system, which comprises:

an ISCO pump, a pressure tracking pump, a first intermediate container, a second intermediate container, a water bath, a microfluidic manifold, and an imaging device; the ISCO pump is respectively connected with a first intermediate container and a second intermediate container in a first pipeline and a second pipeline through a three-way valve in the first pipeline, the first intermediate container is connected to the inside of the microfluidic branching device through a second needle valve and a first four-way valve in sequence, the second intermediate container is connected to the inside of the microfluidic branching device through a fourth needle valve and a second four-way valve in sequence, an imaging device is connected to the upper part of the microfluidic branching device, a vacuum pump is connected to the second four-way valve through a sixth needle valve in the fourth pipeline, a pressure tracking pump is connected to the first four-way valve through a fifth needle valve in the third pipeline, and a water bath box is connected with a thermal fluid circulation interface of the microfluidic branching device; the first four-way valve and the second four-way valve are also respectively connected with a first emptying valve and a second emptying valve.

Further, the imaging device comprises an optical microscope, a camera and a computer, wherein the optical microscope is installed above the micro-fluid splitter.

Furthermore, the side surface of the microfluid splitter comprises a water bath circulation interface which is used for connecting the water bath box and the microfluid splitter, constant temperature water circulates between the water bath box and the microfluid splitter, and the constant temperature water heats the nano fluid chip to the real formation temperature in the forms of heat conduction and heat radiation.

Further, a nanofluid chip is installed in the microfluid splitter, a first shale oil inlet and a first fracturing fluid inlet are respectively formed in the left side and the right side of the upper portion of the nanofluid chip, the first shale oil inlet is connected to the left end of the capillary tube group through a first shale oil microchannel, and the first fracturing fluid inlet is connected to the right end of the capillary tube group through a first fracturing fluid microchannel; the left side and the right side of the lower part of the nanofluid chip are respectively provided with a second shale oil inlet and a second fracturing fluid inlet, the second shale oil inlet is respectively connected to the left ends of the first porous medium and the second porous medium through a second shale oil microchannel, and the second fracturing fluid inlet is respectively connected to the right ends of the first porous medium and the second porous medium through a second fracturing fluid microchannel.

Furthermore, the first intermediate container is connected to the first shale oil inlet or the second shale oil inlet through the second needle valve and the first four-way valve in sequence; and the second intermediate container is connected to the first fracturing fluid inlet or the second fracturing fluid inlet through a fourth needle valve and a second four-way valve in sequence.

Furthermore, the capillary group comprises 6 long straight capillaries with different diameters, and is used for researching the contact angle change rule under different pore sizes.

Further, a fluid receiving chip is installed in the microfluidic splitter, a first formation water inlet and a first CO2 inlet are respectively formed in the upper portion and the lower portion of the left side of the fluid receiving chip, the first formation water inlet is connected to the pore-karst cave type porous medium through a first formation water micro-channel, and the first CO2 inlet is connected to the other end of the pore-karst cave type porous medium through a first CO2 micro-channel; and the upper part and the lower part of the right side of the chip are respectively provided with a second formation water inlet and a second CO2 inlet, the second formation water inlet is connected to the pore-crack-karst cave type porous medium through a second formation water micro-channel, and the second CO2 inlet is connected to the other end of the pore-crack-karst cave type porous medium through a second CO2 micro-channel.

Furthermore, the first intermediate container is connected to the first formation water inlet or the second formation water inlet inside the micro-fluid splitter through the second needle valve and the first four-way valve in sequence, and the second intermediate container is connected to the first CO2 inlet or the second CO2 inlet inside the micro-fluid splitter through the fourth needle valve and the second four-way valve in sequence.

Further, pore-cavern type porous media include pores and caverns; pore-fracture-cavern type porous media include pores, fractures, and caverns.

The second aspect of the invention provides a method for measuring imbibition parameters based on the imbibition visualization system resistant to high temperature and high pressure in the first aspect, which comprises the following steps:

injecting liquid or gas to be measured into the first intermediate container and the second intermediate container;

setting parameters of a water bath tank and a pressure tracking pump;

and opening a corresponding valve to start imbibition, recording the imbibition process by using an imaging device, and calculating imbibition parameters.

The above one or more technical solutions have the following beneficial effects:

the invention provides a method for measuring imbibition parameters, which can respectively realize in-situ measurement of a contact angle and imbibition efficiency in a high-temperature and high-pressure limited space through a capillary group and a porous medium chip structure, and can observe the oil-water two-phase interface change and the oil-water distribution condition in a dynamic imbibition process. And the visualization and quantitative evaluation of the influence of the salt crystallization dynamic process, the salt crystallization distribution and the salt crystallization on the seepage capability of the microscopic pore throat structure can also be realized. In addition, the nano-pore size constructed by the nano-fluidic technology is accurate, the result repeatability is high, the method can be used for quantitative verification and calculation of an imbibition model (such as an LW equation), and a new idea is developed for imbibition experiments and theoretical research.

The invention provides a high-temperature and high-pressure resistant imbibition visualization system, which can simulate high-temperature and high-pressure conditions, realize the visual representation of an imbibition process through a nanofluidic and visualization technology, calculate the imbibition efficiency through an image processing technology, and measure the contact angle in a limited pore in situ, so that the imbibition visualization system realizes the simulation of the imbibition process under the high-temperature and high-pressure conditions and the visual observation of the effect of the complete imbibition process, and provides a new experimental means for imbibition research.

Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is an overall structure diagram of the imbibition visual system resistant to high temperature and high pressure according to the invention;

FIG. 2 is a design diagram of the overall structure of a nanofluid chip used in the high-temperature high-pressure dynamic imbibition process of a shale oil reservoir in the first embodiment of the present invention;

FIG. 3 is a structural diagram of a capillary group for measuring dynamic changes in contact angle at different pore sizes according to one embodiment of the present invention;

FIG. 4 is a design diagram of a partial structure of a 50nm first porous medium for measuring imbibition efficiency according to an embodiment of the invention;

FIG. 5 is a partial structural design diagram of a 500 nm second porous medium for measuring imbibition efficiency according to a first embodiment of the invention;

FIG. 6 is a design diagram of the overall structure of a nanofluid chip used in the salt crystallization process in the CO2 saltwater layer sequestration in the second embodiment of the present invention;

FIG. 7 is a partial structure diagram of a pore-cavity porous medium in a microfluidic chip according to a second embodiment of the present invention;

FIG. 8 is a partial structure diagram of a pore-crack-cave type porous medium in a microfluidic chip according to a second embodiment of the present invention;

FIG. 9 is the contact angle after 2 seconds of imbibition in a 500 nm pore measured in example three of the invention;

FIG. 10 is a visualized image of salt crystal distribution in the salt crystallization process of the pore-crack-cave type porous medium in the fifth embodiment of the present invention;

wherein 1-ISCO pump, 2-first intermediate container, 3-second intermediate container, 4-microfluidic splitter, 5-nanofluidic chip, 6-water bath tank, 7-vacuum pump, 8-pressure tracking pump, 9-optical microscope, 10-camera, 11-computer, 1201-first line, 1202-second line, 1203-third line, 1204-fourth line, 1301-three-way valve, 1302-first four-way valve, 1303-second four-way valve, 1401-first needle valve, 1402-second needle valve, 1403-third needle valve, 1404-fourth needle valve, 1405-fifth needle valve, 1406-sixth needle valve, 1501-first vent valve, 1502-second vent valve, 501-first shale oil inlet, 502-first fracturing fluid inlet, 503-first shale oil microchannel, 504-first fracturing fluid microchannel, 505-capillary bank, 506-second shale oil inlet, 507-second fracturing fluid inlet, 508-second shale oil microchannel, 509-second fracturing fluid microchannel, 5010-first porous medium, 5011-second porous medium, 5012-single capillary tube, 5013-length marker, 5014-first matrix, 5015-second matrix; 701-first formation water inlet, 702-first CO2 inlet, 703-first formation water microchannel, 704-first CO2 microchannel, 705-pore-karst cave type porous medium, 706-second formation water inlet, 707-second CO2 inlet, 708-second formation water microchannel, 709-second CO2 microchannel, 7010-pore-fracture-karst cave type porous medium, 7011-pore, 7012-karst cave, 7013-microfracture.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

The invention provides a high-temperature and high-pressure resistant imbibition visualization system, as shown in fig. 1, comprising:

ISCO pump 1, pressure tracking pump 8, first intermediate container 2, second intermediate container 3, water bath 6, microfluidic manifold 4, and imaging device; the ISCO pump 1 is respectively connected with a first intermediate container 2 and a second intermediate container 3 in a first pipeline 1201 and a second pipeline 1202 through a three-way valve 1301 in the first pipeline 1201, the first intermediate container 2 is connected to the interior of a microfluidic splitter 4 through a second needle valve 1402 and a first four-way valve 1302 in sequence, the second intermediate container 3 is connected to the interior of the microfluidic splitter 4 through a fourth needle valve 1404 and a second four-way valve 1303 in sequence, an imaging device is connected above the microfluidic splitter 4, a vacuum pump 7 is connected to the second four-way valve 1303 through a sixth needle valve 1406 in the fourth pipeline 1204, a pressure tracking pump 8 is connected to the first four-way valve 1302 through a fifth needle valve 1405 in a third pipeline 1203, and a water bath box 6 is connected with a 4-hot fluid circulation interface of the microfluidic splitter; the first four-way valve 1302 and the second four-way valve 1303 are further connected to a first vent valve 1501 and a second vent valve 1502, respectively.

Optionally, the vacuum pump is used for vacuumizing the whole experiment system, so that residual air in the whole system is removed, and experiment errors are reduced.

Optionally, the ISCO pump is used to drive the intermediate container at a constant pressure or constant speed to provide a constant pressure or constant flow rate to the injection fluid in the intermediate container, the accuracy of the ISCO pump is 0.0001ml/min, and the working pressure is less than or equal to 68MPa.

Optionally, the pressure tracking pump is used to set and adjust a constant outlet pressure (back pressure) during the displacement process, and simulate the formation pressure during the fracturing fluid imbibition process.

Optionally, a water bath is used to heat the microfluidic splitter and nanofluidic chip to simulate actual formation temperatures.

The imaging device comprises an optical microscope, a camera and a computer, wherein the optical microscope is arranged above the microfluid splitter.

The side surface of the microfluid splitter comprises a water bath circulation interface which is used for connecting a water bath box and the microfluid splitter, constant temperature water circulates between the water bath box and the microfluid splitter, and the constant temperature water heats the nanofluid chip to the real formation temperature in the forms of heat conduction and heat radiation.

The first embodiment is as follows:

a high-temperature and high-pressure resistant imbibition visualization system in the first aspect, which is used in a high-temperature and high-pressure dynamic imbibition process of a shale oil reservoir, as shown in fig. 2, a high-temperature and high-pressure resistant nano-fluid chip is installed inside a micro-fluid splitter, and the temperature and pressure range of the nano-fluid chip in this embodiment is not more than 200 ℃ and less than 50MPa. The nanofluid chip comprises a substrate and a cover plate which are sealed, the substrate is provided with two pairs of through holes, the first pair of through holes are positioned at two sides (the upper left part and the upper right part) of the top of the substrate and comprise a first shale oil inlet 501 and a first fracturing fluid inlet 502, a first shale oil micro-channel 503, a capillary tube group 505 and a first fracturing fluid micro-channel 504 are arranged between the first pair of through holes, the first shale oil inlet 501 is connected with the first shale oil micro-channel 503, the first fracturing fluid inlet 502 is connected with the first fracturing fluid micro-channel 504, the first shale oil micro-channel 503 and the first fracturing fluid micro-channel 504 are respectively connected with two ends of the capillary tube group 505, the capillary tube group 505 consists of a plurality of long straight capillaries with different diameters, and the first shale oil inlet 501, the first shale oil micro-channel 503, the capillary 505, the first fracturing fluid micro-channel 504 and the first fracturing fluid inlet 502 jointly form a physical model for measuring a contact angle in a seepage process; the second through hole pair is positioned on two sides (the left lower part and the right lower part) of the bottom of the substrate and comprises a second shale oil inlet 506 and a second fracturing fluid inlet 507, a second shale oil micro-channel 508, a first porous medium 5010, a second porous medium 5011 and a second fracturing fluid micro-channel 509 are arranged between the second through hole pair, the second shale oil inlet 506 is connected with the second shale oil micro-channel 508, the second fracturing fluid inlet 507 is connected with the second fracturing fluid micro-channel 509, the second shale oil micro-channel 508 and the second fracturing fluid micro-channel 509 are respectively connected with two ends of the first porous medium 5010 and the second porous 5011, and therefore the second shale oil inlet 506, the second shale oil micro-channel 508, the first porous medium 5010, the second porous medium 5011, the second fracturing fluid micro-channel 509 and the second fracturing fluid inlet 507 jointly form a physical model for measuring the absorption efficiency of fracturing fluid in porous media with different nano sizes;

specifically, the left side and the right side of the upper part of the nanofluid chip are respectively provided with a first shale oil inlet and a first fracturing fluid inlet, the first shale oil inlet is connected to the left end of the capillary group through a first shale oil microchannel, and the first fracturing fluid inlet is connected to the right end of the capillary group through a first fracturing fluid microchannel; the left side and the right side of the lower part of the nanofluid chip are respectively provided with a second shale oil inlet and a second fracturing fluid inlet, the second shale oil inlet is respectively connected to the left ends of the first porous medium and the second porous medium through a second shale oil microchannel, and the second fracturing fluid inlet is respectively connected to the right ends of the first porous medium and the second porous medium through a second fracturing fluid microchannel. In this embodiment, the widths and depths of the first fracturing fluid micro-channels 504 are all 200 μm and 100 μm; the second shale oil microchannel 508 and the second fracturing fluid microchannel 509 each have a width of 200 μm and a depth of 100 μm.

Optionally, the first intermediate container is connected to the first shale oil inlet or the second shale oil inlet sequentially through the second needle valve and the first four-way valve; and the second intermediate container is connected to the first fracturing fluid inlet or the second fracturing fluid inlet through a fourth needle valve and a second four-way valve in sequence.

Alternatively, as shown in fig. 3, the capillary group comprises 6 long straight capillaries with different diameters, and is used for researching the contact angle change rule under different pore sizes. The 6 capillaries are 16mm in length, 10, 20, 40, 50, 75 and 100 μm in width from small to large, 50, 100, 200, 500, 750 and 1000nm in corresponding depth respectively, and the length markers 5013 are used for measuring the length and providing reference points for image acquisition and analysis.

Alternatively, as shown in fig. 4, a first porous medium 5010 within a nanofluidic chip, the first porous medium 5010 was used to study the imbibition efficiency in porous media with pore size 50nm, the porous medium was 16mm long and 200 μm wide, and comprised a first substrate 5014 and a nanopore formed between the substrates, the first substrate was 5 μm in diameter, the nanopore was 5 μm wide and 50nm deep, and a length marker 5013 was used to measure the length and provide a reference point for image acquisition and analysis.

Alternatively, as shown in fig. 5, a second porous medium 5011 within the nanofluidic chip, the second porous medium 5011 was used to study the imbibition efficiency in porous media with pore size 100nm, the porous medium was 16mm long and 200 μm wide, and included a second substrate 5015 and the nanopores formed between the substrates, the second substrate was 10 μm in diameter, the nanopores were 10 μm wide and 100nm deep, and length markers 5013 were used to measure the length and provide reference points for image acquisition and analysis.

Optionally, an optical microscope is installed above the microfluidic splitter and used for observing the fluid distribution and the contact angle of the crude oil displacement process of the fracturing fluid imbibition in the nanofluidic chip in real time, transmitting and storing images in a computer in real time through a camera, analyzing the recorded image sequence by using image processing software, and calculating or measuring imbibition parameters such as imbibition efficiency and contact angle.

Optionally, in this embodiment, the first intermediate container is made of 316L stainless steel, is resistant to temperature of 150 ℃, and is resistant to pressure of 50MPa, and is used for containing crude oil; the second intermediate container is made of corrosion-resistant HC-276, can resist the temperature of 150 ℃ and withstand the pressure of 50MPa, and is used for containing the fracturing fluid.

Example two:

the high-temperature and high-pressure resistant imbibition visualization system is used for a salt crystallization process in CO2 saline water layer sealing, as shown in FIG. 6, a high-temperature and high-pressure resistant nano-fluid chip is installed in a micro-fluid splitter, and the temperature and pressure range of the nano-fluid chip in the embodiment is not more than 200 ℃ and is less than 50MPa. The nanofluid chip comprises a substrate and a cover plate which are sealed, the substrate is provided with two pairs of through holes, the first pair of through holes are positioned at the same side (the upper left part and the lower left part) of the substrate and comprise a first formation water inlet 701 and a first CO2 inlet 702, a first formation water micro-channel 703, a pore-cavern type porous medium 705 and a first CO2 micro-channel 704 are arranged between the first pair of through holes, the first formation water inlet 701 is connected with the first formation water micro-channel 703, the other end of the first formation water micro-channel 703 is connected with the pore-cavern type porous medium 705, the first CO2 inlet 702 is connected with the other end of the pore-cavern type porous medium 705 through the first CO2 micro-channel 704, and therefore a CO2 displacement formation water passage in the pore-cavern type porous medium 705 is formed; the second through hole pair is positioned on the same side (upper right part and lower right part) of the opposite side of the substrate and comprises a second formation water inlet 706 and a second CO2 inlet 707, a second formation water micro channel 708, a pore-fracture-karst cave type porous medium 7010 and a second CO2 micro channel 709 are arranged between the second through hole pair, the second formation water inlet 706 is connected with the second formation water micro channel 708, the other end of the second formation water micro channel 708 is connected with the pore-fracture-karst cave type porous medium 7010, and the second CO2 inlet 707 is connected with the other end of the pore-fracture-karst cave type porous medium 7010 through the second CO2 micro channel 709, so that a CO2 displacement formation water passage in the pore-fracture-karst cave type porous medium 7010 is formed.

Specifically, the upper part and the lower part of the left side of the nano fluid chip are respectively provided with a first formation water inlet and a first CO2 inlet, the first formation water inlet is connected to the pore-karst cave type porous medium through a first formation water micro-channel, and the first CO2 inlet is connected to the other end of the pore-karst cave type porous medium through a first CO2 micro-channel; the upper part and the lower part of the right side of the chip are respectively provided with a second formation water inlet and a second CO2 inlet, the second formation water inlet is connected to the pore-crack-karst cave type porous medium through a second formation water micro-channel, and the second CO2 inlet is connected to the other end of the pore-crack-karst cave type porous medium through a second CO2 micro-channel. In this embodiment, the first CO2 microchannel, the first formation water microchannel, the first CO2 microchannel, and the second formation water microchannel in the microfluidic chip all have widths of 200 μm and depths of 100 μm.

Optionally, the first intermediate container is connected to the first formation water inlet or the second formation water inlet inside the microfluidic splitter through a second needle valve and a first four-way valve in sequence, and the second intermediate container is connected to the first CO2 inlet or the second CO2 inlet inside the microfluidic splitter through a fourth needle valve and a second four-way valve in sequence.

Alternatively, as shown in fig. 7, the pore-cavern type porous medium includes pores and caverns; the width of the pore 7011 is 2 μm, the depth is 1 μm, the shape of the karst cave 7012 is various, the width is 100 μm-200 μm, and the depth is 100 μm.

Alternatively, as shown in fig. 8, the pore-fracture-cavern type porous medium includes pores, fractures, and caverns. The width and the depth of the pore 7011 are respectively 2 μm and 1 μm, the width and the depth of the crack 7013 are respectively 20 μm and 10 μm, and the width and the depth of the karst cave 7012 are respectively 100 μm to 200 μm and 100 μm.

Optionally, in this embodiment, the first intermediate container is a high-salt-resistant intermediate container made of high-salt-resistant HC-276, is resistant to temperature of 150 ℃, and is resistant to pressure of 50MPa, and is used for containing high-salinity formation water; the second intermediate container is a CO 2-resistant intermediate container, is made of HC-276 material resistant to CO2 corrosion, can resist temperature of 150 ℃ and withstand pressure of 50MPa, and is used for containing CO2.

The second aspect of the invention provides a imbibition parameter measuring method based on the imbibition visualization system with high temperature and high pressure resistance in the first aspect, which comprises the following steps:

injecting the liquid or gas to be measured into the first intermediate container and the second intermediate container;

setting parameters of a water bath tank and a pressure tracking pump;

and opening a corresponding valve to start imbibition, recording the imbibition process by using an imaging device, and calculating imbibition parameters.

Example three:

the imbibition parameter measuring method of the second aspect is used for measuring a contact angle in an imbibition process, and the experimental method of the embodiment specifically comprises the following processes:

(1) Filling shale oil and fracturing fluid into a first intermediate container 2 and a second intermediate container 3 respectively, starting a water bath tank 6, and setting the heating temperature to be 80 ℃ of the formation temperature; opening a first needle valve 1401, a second needle valve 1402, a third needle valve 1403, a fourth needle valve 1404, a first emptying valve 1501 and a second emptying valve 1502, starting the ISCO pump 1 to empty the upstream pipeline and the container, closing the first emptying valve 1501, the second emptying valve 1502, the first needle valve 1401, the second needle valve 1402, the third needle valve 1403 and the fourth needle valve 1404 after the emptying valves generate continuous fluid, and closing the ISCO pump 1; the fifth needle valve 1405 and the sixth needle valve 1406 are opened, the vacuum pump 7 is started, and the fifth needle valve 1405 and the sixth needle valve 1406 are closed after 2 hours of vacuum pumping.

(2) The first needle valve 1401 and the second needle valve 1402 are opened, the ISCO pump 1 is started, the shale oil enters the capillary tube group 505 through the micro-fluid splitter 4, the first shale oil inlet 501 and the first shale oil micro-channel 503 at a constant pressure of 15MPa, the pump is stopped immediately after the shale oil is observed at the first fracturing fluid inlet 502, and simultaneously the first needle valve 1401 and the second needle valve 1402 are closed.

(3) And (3) opening the third needle valve 1403, the fourth needle valve 1404 and the fifth needle valve 1405, starting the pressure tracking pump 8, setting the outlet pressure to be 15MPa (simulating the formation pressure), starting the ISCO pump 1, enabling the fracturing fluid to enter the first fracturing fluid microchannel 504 through the microfluidic splitter 4 at the constant pressure of 15.01MPa through the inlet of the first fracturing fluid microchannel 502, stopping the pump immediately when the oil-water interface in the first fracturing fluid microchannel 504 is 2mm away from the port of the capillary tube group, and enabling the fracturing fluid to slowly enter the capillary tube group through the seepage action to replace shale oil. The contact angle after imbibition for 2 seconds is shown in fig. 9, where the highlighted portion in the capillary is the fracturing fluid and the dark portion is shale oil.

(4) In the whole experiment process, the optical microscope 9, the camera 10 and the computer 11 are always kept in running and video recording states, and the stored image sequence is processed by using image processing software imageJ to measure the contact angle in the imbibition process.

Example four:

the method for measuring the imbibition parameters in the second aspect is used for measuring the imbibition efficiency in the imbibition process, and the experimental method comprises the following specific processes:

(1) Filling shale oil and fracturing fluid into a first intermediate container 2 and a second intermediate container 3 respectively, starting a water bath box 6, and setting the heating temperature to be 80 ℃ of the formation temperature; opening a first needle valve 1401, a second needle valve 1402, a third needle valve 1403, a fourth needle valve 1404, a first emptying valve 1501 and a second emptying valve 1502, starting the ISCO pump 1 to empty the upstream pipeline and the container, closing the first emptying valve 1501, the second emptying valve 1502, the first needle valve 1401, the second needle valve 1402, the third needle valve 1403 and the fourth needle valve 1404 after the emptying valves generate continuous fluid, and closing the ISCO pump 1; the fifth needle valve 1405 and the sixth needle valve 1406 are opened, the vacuum pump 7 is started, and the fifth needle valve 1405 and the sixth needle valve 1406 are closed after 2 hours of vacuum pumping.

(2) The first needle valve 1401, the second needle valve 1402 are opened, the ISCO pump 1 is started to feed shale oil through the microfluidic splitter 4, the second shale oil inlet 506, the second shale oil microchannel 508 into the first porous medium 5010 and the second porous medium 5011 at a constant pressure of 15MPa, the pump is stopped immediately after the shale oil is observed at the second fracturing fluid inlet 507, and the first needle valve 1401, the second needle valve 1402 are closed.

(3) And (3) opening the third needle valve 1403, the fourth needle valve 1404 and the fifth needle valve 1405, starting the pressure tracking pump 8, setting the outlet pressure to be 15MPa (simulating the formation pressure), starting the ISCO pump 1, enabling the fracturing fluid to enter the second fracturing fluid micro-channel 509 through the inlet of the second fracturing fluid micro-channel 507 through the micro-fluid splitter 4 at the constant pressure of 15.01MPa, stopping the pump immediately when the oil-water interface in the second fracturing fluid micro-channel 509 is 2mm away from the port of the first porous medium 5010, and enabling the fracturing fluid to slowly enter the first porous medium 5010 and the second porous medium 5011 through the imbibition effect to replace the shale oil.

(4) In the whole experiment process, the optical microscope 9, the camera 10 and the computer 11 are always kept in running and video recording states, the stored image sequence is processed by using image processing software imageJ, and the imbibition efficiency is calculated according to the oil phase distribution area and the fracturing fluid distribution area in the whole porous medium.

Example five:

the method for measuring the imbibition parameter in the second aspect is used for measuring the salt crystallization process in the pore-crack-karst cave type porous medium, and the experimental method in the embodiment specifically comprises the following processes:

(1) Respectively filling formation water (high-concentration brine) and CO2 in a high-salt resistant intermediate container 2 and a CO2 resistant intermediate container 3, starting a water bath box 5, and setting the heating temperature to 70 ℃ of the formation temperature; opening a first needle valve 1401, a second needle valve 1402, a third needle valve 1403, a fourth needle valve 1404, a first emptying valve 1501 and a second emptying valve 1502, starting the ISCO pump 1, emptying an upstream pipeline through the emptying valves, closing the first emptying valve 1501, the second emptying valve 1502, the first needle valve 1401, the second needle valve 1402, the third needle valve 1403, the fourth needle valve 1404 after the emptying valves generate continuous fluid, and closing the ISCO pump 1; the fifth needle valve 1405 and the sixth needle valve 1406 are opened, the vacuum pump 7 is started, and the fifth needle valve 1405 and the sixth needle valve 1406 are closed after 2 hours of vacuum pumping.

(2) The first and second needle valves 1401, 1402 are opened and the ISCO pump 1 is started to feed formation water at a constant pressure through the microfluidic splitter 4 into the second formation water inlet 706, and after formation water is observed at the second CO2 inlet 707, the pump is stopped and the first and second needle valves 1401, 1402 are closed.

(3) Opening the third needle valve 1403, the fourth needle valve 1404, opening the fifth needle valve 1405, starting the pressure tracking pump 8, setting a constant outlet pressure, starting the ISCO pump 1, introducing CO2 into the second CO2 inlet 707 through the microfluidic splitter 4 at a constant pressure to displace formation water, simultaneously shooting the crystallization dynamic process inside the porous medium in real time through the computer 11, and shooting the distribution position and crystal shape of salt crystals in the porous medium after the formation water is completely displaced.

(4) And processing the stored image sequence by using image processing software imageJ, and analyzing the crystal property, the crystal quantity and the pore-throat seepage capacity change.

As shown in fig. 10, in the visualized image of the distribution of salt crystals in the pore-crack-cavern type porous medium measured in this example, different shapes (needle-like, plate-like) and different amounts of salt crystals were observed in the pores, cracks and caverns.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims (10)

1. The utility model provides a visual system of imbibition of high temperature and high pressure resistant which characterized in that includes: an ISCO pump, a pressure tracking pump, a first intermediate container, a second intermediate container, a water bath, a microfluidic manifold, and an imaging device; the ISCO pump is respectively connected with a first intermediate container and a second intermediate container in a first pipeline and a second pipeline through a three-way valve in the first pipeline, the first intermediate container is connected to the inside of the microfluidic branching device through a second needle valve and a first four-way valve in sequence, the second intermediate container is connected to the inside of the microfluidic branching device through a fourth needle valve and a second four-way valve in sequence, an imaging device is connected to the upper part of the microfluidic branching device, a vacuum pump is connected to the second four-way valve through a sixth needle valve in the fourth pipeline, a pressure tracking pump is connected to the first four-way valve through a fifth needle valve in the third pipeline, and a water bath box is connected with a thermal fluid circulation interface of the microfluidic branching device; the first four-way valve and the second four-way valve are also respectively connected with a first emptying valve and a second emptying valve.

2. The imbibition visualization system of claim 1, wherein the imaging device comprises an optical microscope, a camera, and a computer, the optical microscope being mounted above the microfluidic splitter.

3. The high temperature and high pressure resistant imbibition visualization system of claim 1, wherein the lateral surface of the microfluidic manifold comprises a water bath circulation interface for connecting the water bath tank and the microfluidic manifold, constant temperature water circulates between the two to heat the nanofluidic chip to the real formation temperature in the form of heat conduction and heat radiation.

4. The imbibition visualization system of claim 1, wherein a nanofluid chip is installed inside the microfluidic splitter, the left and right sides of the upper portion of the nanofluid chip are respectively provided with a first shale oil inlet and a first fracturing fluid inlet, the first shale oil inlet is connected to the left end of the capillary tube group through a first shale oil microchannel, and the first fracturing fluid inlet is connected to the right end of the capillary tube group through a first fracturing fluid microchannel; the left side and the right side of the lower part of the nanofluid chip are respectively provided with a second shale oil inlet and a second fracturing fluid inlet, the second shale oil inlet is respectively connected to the left ends of the first porous medium and the second porous medium through a second shale oil microchannel, and the second fracturing fluid inlet is respectively connected to the right ends of the first porous medium and the second porous medium through a second fracturing fluid microchannel.

5. The imbibition visualization system of claim 4, wherein the first intermediate container is connected to the first shale oil inlet or the second shale oil inlet sequentially through the second needle valve and the first four-way valve; and the second intermediate container is connected to the first fracturing fluid inlet or the second fracturing fluid inlet through a fourth needle valve and a second four-way valve in sequence.

6. The imbibition visualization system of claim 5, wherein the capillary group comprises 6 long straight capillaries with different diameters, and is used for researching the contact angle change rule under different pore sizes.

7. The imbibition visualization system of claim 1, wherein a nanofluidic chip is installed inside the microfluidic splitter, the upper and lower parts of the left side of the nanofluidic chip are respectively provided with a first formation water inlet and a first CO2 inlet, the first formation water inlet is connected to the pore-cavern type porous medium through a first formation water microchannel, and the first CO2 inlet is connected to the other end of the pore-cavern type porous medium through a first CO2 microchannel; and the upper part and the lower part of the right side of the chip are respectively provided with a second formation water inlet and a second CO2 inlet, the second formation water inlet is connected to the pore-crack-karst cave type porous medium through a second formation water micro-channel, and the second CO2 inlet is connected to the other end of the pore-crack-karst cave type porous medium through a second CO2 micro-channel.

8. The imbibition visualization system of claim 7, wherein the first intermediate container is connected to the first formation water inlet or the second formation water inlet inside the microfluidic splitter sequentially through a second needle valve and a first four-way valve, and the second intermediate container is connected to the first CO2 inlet or the second CO2 inlet inside the microfluidic splitter sequentially through a fourth needle valve and a second four-way valve.

9. The imbibition visualization system of claim 8, wherein the pore-cavern type porous medium comprises pores and a cavern; pore-fracture-cavern type porous media include pores, fractures, and caverns.

10. A imbibition parameter measuring method based on the imbibition visualization system resistant to high temperature and high pressure of any one of claims 1-9, comprising the following steps:

injecting liquid or gas to be measured into the first intermediate container and the second intermediate container;

setting parameters of a water bath tank and a pressure tracking pump;

and opening a corresponding valve to start imbibition, recording the imbibition process by using an imaging device, and calculating imbibition parameters.

Images